Thursday, March 31, 2011

When Galaxies Collide

What is cooler than seeing an awesome image of colliding galaxies taken with an 8-meter telescope? Not much, except perhaps knowing that this particular image was due in part to some work done by high school students.

This image of galaxies NGC 6872 and IC 4979 is result of a winning entry submitted by Sydney Girls High School Astronomy Club as part of a contest by put on by Gemini Observatory.  Australian students take note, they are running the contest again this year

Here are some details on the collision from the Gemini press release:

The primary galaxy in the image (NGC 6872) exemplifies what happens when galaxies interact and their original structure and form is distorted. When galaxies like these grapple with each other, gravity tugs at their structures, catapulting spiral arms out to enormous distances. In NGC 6872, the arms have been stretched out to span hundreds of thousands of light-years—many times further than the spiral arms of our own Milky Way galaxy. Over hundreds of millions of years, NGC 6872’s arms will fall back toward the central part of the galaxy, and the companion galaxy (IC 4970) will eventually be merged into NGC 6872. The coalescence of galaxies often leads to a burst of new star formation. Already, the blue light of recently created star clusters dot the outer reaches of NGC 6872’s elongated arms. Dark fingers of dust and gas along the arms soak up the visible light. That dust and gas is the raw material out of which future generations of stars could be born.
You can get a 13.3 TIFF version of the image here.

Wednesday, March 16, 2011

Gas Clouds Colliding at 1 Million Kilometers Per Hour = Beautiful

Wouldn't you agree?

The image above is of the star-forming region known as NGC 6729 and is the latest image released from the European Southern Observatory's Very Large Telescope.

At a distance of only about 400 light years, NGC 6729 is part of one of the closest stellar nurseries to the Earth. It is located in the southern constellation of Corona Australis. Follow the link above for more information and click on the image to see it in even higher resolution or click here to see a glorious 9 MB tiff version. 

Tuesday, March 15, 2011

Speaking at Corning Musuem of Glass Next Week

I don't plan on spending too much time on Palomar-related stuff here at Visible Suns (look for that at my Palomar Skies blog), but on Thursday, March 24 I will be giving a public talk at the Corning Museum of Glass. The talk will focus on Palomar Observatory's research and discoveries.

Corning Glass Works was the birthplace of Palomar's 200-inch mirror.

That is me with the mirror when it was pulled from the Hale Telescope for washing last November.

Follow the link for more information on the talk or to make reservations to attend.

Friday, March 11, 2011

The Eye of Sauron - A Multi-Wavlength View

It is no secret that virtually all big galaxies have a supermassive black hole in their cores. This new view shows the environment immediately around the active black hole that lies in the heart  of the Seyfert galaxy known as NGC 4151.

From the team at the Chandra X-Ray Observatory:

This composite image shows the central region of the spiral galaxy NGC 4151, dubbed the "Eye of Sauron" by astronomers for its similarity to the eye of the malevolent character in "The Lord of the Rings". In the "pupil" of the eye, X-rays (blue) from the Chandra X-ray Observatory are combined with optical data (yellow) showing positively charged hydrogen ("H II") from observations with the 1-meter Jacobus Kapteyn Telescope on La Palma. The red around the pupil shows neutral hydrogen detected by radio observations with the NSF's Very Large Array. This neutral hydrogen is part of a structure near the center of NGC 4151 that has been distorted by gravitational interactions with the rest of the galaxy, and includes material falling towards the center of the galaxy. The yellow blobs around the red ellipse are regions where star formation has recently occurred.

A recent study has shown that the X-ray emission was likely caused by an outburst powered by the supermassive black hole located in the white region in the center of the galaxy. Evidence for this idea comes from the elongation of the X-rays running from the top left to the bottom right and details of the X-ray spectrum. There are also signs of interactions between a central source and the surrounding gas, particularly the yellow arc of H II emission located above and to the left of the black hole.

Two different scenarios to explain the X-ray emission have been proposed. One possibility is that the central black hole was growing much more quickly about 25,000 years ago (in Earth's time frame) and the radiation from the material falling onto the black hole was so bright that it stripped electrons away from the atoms in the gas in its path. X-rays were then emitted when electrons recombined with these ionized atoms.

The second possibility also involved a substantial inflow of material into the black hole relatively recently. In this scenario the energy released by material flowing into the black hole in an accretion disk created a vigorous outflow of gas from the surface of the disk. This outflowing gas directly heated gas in its path to X-ray emitting temperatures. Unless the gas is confined somehow, it would expand away from the region in less than 100,000 years. In both of these scenarios, the relatively short amount of time since the last episode of high activity by the black hole may imply such outbursts occupy at least about 1% of the black hole's lifetime.

NGC 4151 is located about 43 million light years away from the Earth and is one of the nearest galaxies that contains an actively growing black hole. Because of this proximity, it offers one of the best chances of studying the interaction between an active supermassive black hole and the surrounding gas of its host galaxy. Such interaction, or "feedback", is recognized to play a key role in the growth of supermassive black holes and their host galaxies. If the X-ray emission in NGC 4151 originates from hot gas heated by the outflow from the central black hole, it would be strong evidence for feedback from active black holes to the surrounding gas on galaxy scales. This would resemble the larger scale feedback, observed on galaxy cluster scales, from active black holes interacting with the surrounding gas, as seen in objects like the Perseus Cluster.

Tuesday, March 8, 2011

Outside In

With any luck Outside In will soon be an IMAX film. Watch and be amazed by Cassini's view of Saturn along with its rings and moons.  Then read about this film project below.

5.6k Saturn Cassini Photographic Animation from stephen v2 on Vimeo.

From their website:
Composed entirely of still photographs using innovative visual techniques developed by the filmmaker, Outside In stretches the boundaries of the motion picture form. The film will feature powerful music by Ferry Corsten, William Orbit, Samuel Barber and melds non-narrative visual poetry & science documentary into a rich experience for audiences.

Outside In is a film that’s both personal and universal, experimental and sincere, science and spirit , non-narrative and documentary. The goal is to use large screen imagery, synchronized to powerful but moving music, to create an experience for those who see it, hear it and feel it.

Using hundreds of thousands of still images manipulated to create full motion, using “2.75D” photographic fly-through technology. The film will be presented in IMAX quality 5.6K resolution on massive screens and concert-level surround systems with a synchronized light show to audiences in planetariums, museums, galleries and limited IMAX release.

Saturday, March 5, 2011

Spitzer's View of the Sunflower Galaxy

Earlier this week the Spitzer Space Telescope team released this image of the spiral galaxy known as the Sunflower Galaxy (M63):

Here is the image caption from the Spitzer team:

The various spiral arm segments of the Sunflower galaxy, also known as Messier 63, show up vividly in this image taken in infrared light by NASA's Spitzer Space Telescope. Infrared light is sensitive to the dust lanes in spiral galaxies, which appear dark in visible-light images. Spitzer's view reveals complex structures that trace the galaxy's spiral arm pattern.

Messier 63 is 37 million light years away -- not far from the well-known Whirlpool galaxy and the associated Messier 51 group of galaxies.

The dust, glowing red in this image, can be traced all the way down into the galaxy's nucleus, forming a ring around the densest region of stars at its center. The dusty patches are where new stars are being born.

The short diagonal line seen on the lower right side of the galaxy's disk is actually a much more distant galaxy, oriented with its edge facing toward us.

Blue shows infrared light with wavelengths of 3.6 and 4.5 microns, green represents 8.0-micron light and red, 24-micron light.

Wednesday, March 2, 2011

App Review: Sky Week

One of the nice things about many astronomy apps for the iPhone & iPad is the ability to tie the built-in GPS, compass & motion sensors to allow a novice user to go out under the sky and identify what is up right then and there.  I will be talking about some of those apps in the near future, but I am going to start off with a simpler, but useful app called Sky Week.

The Sky Week app comes from the folks at Sky & Telescope magazine.  Its function is to give novice & expert stargazers a look at what is of interest in the night sky for the coming week. 

The app loads and if necessary updates quickly, giving the user a display like the one shown here:

What you see is a description of event or two for each of the days in a nine day period.  Further down (below this screen grab) is visibility information on our solar system's eight planets. The app is updated weekly and does not allow you to scroll forward or backward in time to get lists for other weeks.  You can easily set the view to display red text on a black background - a handy feature that allows you to use the app while keeping your eyes adapted to seeing in the dark.

Each of the events listed contains a red VIEW link on the right that opens a simple interactive star chart that is tied the date & time for the event.  Here is a screen grab for the star chart for the event for Friday, March 4, 2011:

It brings up a star chart showing where in the sky to find the star Sirius.  You can pinch to zoom, scroll around the sky with your fingers and use the interface at the bottom to adjust the time you are viewing the chart.  Most often the star chart that pops up is for your current location, but the descriptions are generally written for observers located in the middle of North America.

While finding Sirius is pretty basic (after all it is the brightest star in the night sky), the app contains more detailed information that will please more seasoned amateur astronomers such as when and where to spot an asteroid occultation (when an asteroid can be seen to pass in front of a star) or when the eclipsing binary star Algol hits maximum or minimum brightness.

Sky Week runs smoothly on the iPhone and the iPad where runs in the iPad's native resolution and  is one of the few astronomy apps that I actually use every week. It is available from the iTunes App Store for just $0.99.

Note the version that I reviewed is 1.0.2.

Tuesday, March 1, 2011